TPA2028D1 gain control

Hi Martin,

Welcome to E2E, thank you for your interest in our products.
I was reviewing your configuration setting. I have noticed that limiter level is enabled and the level is very low, even though you set the fixed gain much more high, the signal will be almost the same because It can't vary it due to the limiter level range is very low.
The Limiter level should be disabled, you can disable in the AGC control register.
You could try with the next register setting:
0xC3
0x01 - Attack time
0x01 - Release time
0x01 - Hold time
0x03 - Fixed gain 3 dB, Fixed gain 30 dB - 0x1E
0xE0 - Noise gate threshold, Disables the limiter level
0xC0 - Compression ratio 1:1

Best Regards
Jose Luis Figueroa
Audio Applications Engineer | A-Team

The settings are the same as you specified. May be we have problem because of different files?

www.icloud.com/.../

Look at file in iCloud. I put settings as you specified, but problem still exist. We have one longer audio file which we play with 3 dB, and the other - short one, we play 30 dB. May be AGC still functioning?

We have those two files. One play with 30 dB, the other with 3 dB.

Yes, when we finish to play file we make this. Set volume to 0 and disable amplifier an SW SDN.
void Audio_AmplifierSetVolume(uint16_t volume)
{
    uint8_t transfer_data[] = {0x01, 0xC3, 0x01, 0x01, 0x01, 0x06, 0xE0, 0xC0};
//    uint8_t transfer_data[] = {0x01, 0xC2, 0x02, 0x0A, 0x00, 0x06, 0x5f, 0xC2};
    uint8_t receive_data[5] = {0};
    I2C_M_SETUP_Type TransferCfg;

    //transfer config;
    TransferCfg.sl_addr7bit = (0xB0 >> 1);          /**< Slave address in 7bit mode */
    TransferCfg.tx_data = transfer_data;            /**< Pointer to Transmit data - NULL if data transmit is not used */
    TransferCfg.tx_length = sizeof(transfer_data);  /**< Transmit data length - 0 if data transmit is not used*/
    TransferCfg.tx_count = 0;                       /**< Current Transmit data counter */
    TransferCfg.rx_data = receive_data;             /**< Pointer to Receive data - NULL if data receive is not used */
    TransferCfg.rx_length = 0;                      /**< Receive data length - 0 if data receive is not used */
    TransferCfg.rx_count = 0;                       /**< Current Receive data counter */
    TransferCfg.retransmissions_max = 1;            /**< Max Re-Transmission value */
    TransferCfg.retransmissions_count = 0;          /**< Current Re-Transmission counter */
    TransferCfg.status = 0;                         /**< Current status of I2C activity */
//    TransferCfg.callback = (void *)0;             /**< Pointer to Call back function when transmission complete used in interrupt transfer mode */

    if(volume > 0)
    {
        transfer_data[1] |= (1 << 6);   //  Enable amplifier
        transfer_data[1] &=~(1 << 5);   //  Software shut down off
        transfer_data[5] = (uint8_t)(volume/6);//settings_to_write.sound_vol/100 * 3;
    }
    else
    {
        transfer_data[1] &=~(1 << 6);   //  Disable amplifier
        transfer_data[1] |= (1 << 5);   //  Software shut down on
        transfer_data[5] = 36;  //minimum gain: -28dB;
    }

    I2C_Init(LPC_I2C1, 400000);
    I2C_Cmd(LPC_I2C1, ENABLE);
    I2C_MasterTransferData(LPC_I2C1, &TransferCfg, I2C_TRANSFER_POLLING);
    I2C_DeInit(LPC_I2C1);
}

Yes, code is working properly. On monday I will start to check amplifier. We got new PCBs. More information will be soon.